The last time San Diego made the trip to Denver, the Chargers left with a 27-20 victory. Why couldn't it happen again? For some reason, the Chargers are big underdogs in the AFC divisional playoff game Sunday at Sports Authority Field. The 4:40 p.m. kickoff on CBS is one of the most perplexing matchups of this round. Philip Rivers doesn't get the edge over Peyton Manning, and Manning had 123 more passing yards in that last loss. So it may come down to other factors.

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— We're off. The Chargers, after a Philip Rivers sack, is facing a third-and-17, hand off to Danny Woodhead. The Broncos are whistled for a facemask on the play, giving San Diego an automatic first down. Three plays later, Rivers was down again and facing third-and-16 that he had no chance of converting.

— If this is the way it's going to be, Peyton Manning and his friends playing catch, then this is about to be a long day for the Chargers. Fourteen plays cut up for 86 yards over 7 minutes. That's the kind of methodical, precision playmaking that has separated the Broncos all year, although this is their longest drive of the season. Demaryius Thomas' 2-yard catch capped it, but that followed passes fo Thomas, Eric Decker and Julius Thomas. It came after runs by Montee Ball and Knowshon Moreno. And it included two third-down conversions. What more could the Broncos ask for? Broncos 7, Chargers 0 with 2:25 left in the first quarter .

— Rivers has a temper tantrum when he doesn't get the snap before the playclock expires. He's not laughing, but we are. This is funny.

— Moving on...

SECOND QUARTER

— Manning's pass to Julius Thomas is ripped out by Jahieel Addae and recovered by the Chargers' Donald Butler. It's San Diego ball on their own 44.

— Ryan Matthews appeared bottled up, but he peeled away from the line and sprung free for a big gain. Unfortunately, the drive ended the way the others had -- with a sack. Malik Jackson wrestles Rivers to the ground, and Nick Novak's 53-yard field goal attempt comes up short.

— The Broncos are destroying the Chargers up front right now, and Moreno and Ball are gashing right through it. They are getting to the second level and forcing their will upon the Chargers. Linebacker Manti Te'o sustained a concussion trying to slow Moreno, making them even more vulnerable. On third-and-goal, Manning finds Wes Welker, who comes out of the slot, for a 3-yard touchdown. That drive took 5:13. The Broncos are chewing up the clock and taking away chances from the Chargers. Broncos 14, Chargers 0 .

— Eric Decker is snagged... by the turf monster . He returns a punt 47 yards and then trips and falls on his own. The punter, Mike Scifres, is injured on the tackle attempt when he is kneed in the helmet.

— Manning's pass to Decker, covered by Darrell Stuckey, in the end zone bounced off his chest and into the hands of Butler, who kept his toes barely inbounds for the interception. That ended the half and kept things within inches from being far worse for the Chargers.

— The Chargers stop another Broncos' drive when Welker drops the deep pass from Manning. Unfortunately, Addae injures his left arm. Prater's 45-yard field goal barely squeezes inside the goal post. Broncos 17, Chargers 0 with 9:35 left in the third quarter .

— Prater tries to put it more out of reach, but misses a 47-yard field goal. The score stays the same, but the Chargers have given no indication that they are primed for a fourth quarter run with 1:07 left in the third.

FOURTH QUARTER

— Finally. Rivers finds one of the league's premier recievers, even as a rookie, for a touchdown that the Chargers desperately needed. San Diego must hope that it's not too later. After holding Denver to only a field goal in the third quarter, the Chargers have finally scored as well. Keenan Allen's 16-yard reception is only his second catch of the game. This one was big though, capping a 6-play, 63-yard that only took 3:08. The Chargers need to move at a quick clip, stay strong on defense and make things happen. Broncos 17, Chargers 7 with 12:59 left.

— With three wide receivers split wide left, Manning turns to Moreno for the dagger score. Moreno rushes in from 7 yards out to put a lid on an impressive 81-yard march. Broncos 24, Chargers 7 with 8:12 remaining .

— Single-covering Allen is dangerous. What happens is Allen burning your secondary for 49 yards. On a critical play, Rivers connects with Ronnie Brown for 5 yards. That meant strike time: Rivers gets the ball to—you guessed it—Allen again, who pokes the 16-yard grab across the goal line for a score. Michael Huff tries to keep Allen out, but it doesn't work. But is there enough time left? Broncos 24, Chargers 14 wtih 5:43 left .

— The Chargers tried an onside kick and it worked. It bounced off Decker and was recovered by Richard Marshall...Rivers goes high to Allen for a 17-yard pickup at the Broncos' 47. Allen grabs another 25-yard catch on second-and-5 to advance to the 17. On second-and-10, Brown makes a 5-yard reception. They have to leave with a 30-yard field goal from Novak, but with 3:53 left, they are only down by a score. Broncos 24, Chargers 17 .

PREVIEW

This is what the Broncos don't want and can't afford: an early-round dismissal at the hands of the underdogs. The memory of such a scenario is all to fresh for the Broncos. It was last year this time that they were knocked out by the Baltimore Ravens, 37-34, in overtime. Two years ago, Tim Tebow's team lost to New England, 45-10. It's been a bad run, but with Manning breaking all kinds of records this year, Denver hopes this is their moment.

A welcome addition will be Wes Welker, who has been out with a concussion.